Dual cylinder operator for imparting rotary motion

ABSTRACT

A dual cylinder operator having two parallel cylinders each enclosing two pistons maintained in axially spaced relation by a connector bar, and a torque arm extending crosswise into said cylinders through interfacing cutouts in their inner side walls and having Scotch yoke connections with said connector bars. The torque arm is mounted on a shaft extending transversely between said cylinders for rotating the shaft as fluid pressure is applied selectively to the outer faces of the pistons. The cavity formed between the cylinders in which the torque arm operates contains one end of said shaft and is completely enclosed by four rectangularly arranged plates welded to the cylinders around the cutouts.

United States Patent [191. Shaier DUAL CYLINDER OPERATOR FOR IMPARTING ROTARY MOTION [76] Inventor: Homer J. Shafer, 2300 Park Ave.

I w., Mansfield, Ohio 44906 [22] Filed: Oct. 19, 1972 [21 Appl. No.: 299,046 g Related U.S. Application Data [63] Continuation-impart of Ser. No 72,018, Sept. 14,

1970, Pat. No. 3,709,106.

[ June 25, 1974 Primary Examiner-Paul E. Maslousky Attorney, Agent, or FirmHamilton, Renner &

Kenner s7] ABSTRACT A dual cylinder operator having two parallel cylinders each enclosing two pistons maintained in axially spaced relation by a connector bar, and a torque arm extending crosswise into said cylinders through interfacing cutouts in their inner side walls and having Scotch yoke connections with said connector bars.

The torque arm is mounted on a shaft extending trans- 1 versely between said cylinders for rotating the shaft as fluid pressure is applied selectively to the outer faces of the pistons. The cavity formed between the cylinders in which the torque arm operates contains one 'end of said shaft and .is completely enclosed by four .rectangularly arranged plates welded to the cylinders around the cutouts.

8 Claims, 6 Drawing Figures PAIENTEnJmsmM SHEU 1 (IF Q PATENTEB JUNZS 1874 SHEEI b 0F a DUAL CYLINDER OPERATOR FOR IMPARTING ROTARY MOTION BACKGROUND OF THE INVENTION This application is a continuation-in-part of my copending application Ser. No. 072,018, filedSept. 14,

1970, and allowed'July 31, 1972, now US, Pat. No. 3,709,106.

That application disclosed a single cylinder with axially spaced pistons therein connected by an axial bar, the cylinder between the pistons beingcut out on one side, and a tubular housing for the rotary shaft extending transversely of the cylinder and cut out on one side conforming and welded to the cylinder to form a sealed enclosure communicating with the cylinder and enclosing a crank on the shaft operatively connected to said connector bar between the pistons. Conforming and welding the cylinder and tubular shaft housing around the side cutout is a difficult task, and the crank applies torque on one side only of the shaft.

US. Pat. No. 3,261,266 shows a valve actuator having parallel cylinders with a valve stem extending transversely between the cylinders and having a double crank thereon operatively engaged by intermediate connector bars between each pair of pistons. However, the end of the valve stem and the double crank thereon are enclosed in a separate box-like housing which does not communicate with the cylinders which are mounted on and extend from the ends of the housing. The piston rods pass throughsealing glands in the end walls of the housing. Thus, the housing for the double crank is not adapted or intended to store pressure fluid.

SUMMARY OF THE INVENTION I An object of the present invention is to provide an improved dual cylinder operator having two parallel cylinders and a central housing communicating therewith enclosing a dual arm for transmitting balanced torque.

Another object is to provide an improved dual cylinder operator having a shaft extending transversely between said cylinders and a dual crank arm on the shaft operatively connected to pistons within said cylinders and enclosed within a sealed cavity communicating with said cylinders. v

A further object is to provide an improved dual cylinder operator having two parallel cylinders and a central sealed crank arm housing communicating therewith formed of rectangularly arranged plates' welded to the cylinders around interfacing cut-outs therein.

A still further object is to provide an improved dual cylinder operator having two parallel cylinders with two pistons in each cylinder anda central torque arm within a sealed cavity communicating with said cylinders and operatively connected to both pairs of cylinders by Scotch yoke connections.

Finally, it is an object of the present invention to provide an improved dual cylinder operator which accomplishes all of the stated purposes of copending applica-' tion Ser. No. 072,018, in addition to the additional purposes herein set forth.

' These and other objects are accomplished by the improvements comprising the present invention, a preferred embodiment of which is shown by way of example in the accompanying drawingsand described in de-,

' tail herein. Various modifications and changes in details of construction are contemplated within the scope of the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a longitudinal sectional view of the improved dual operator showing the intennediate position of the torque arm in phantom lines.

DESCRIPTION OF A PREFERRED EMBODIMENT The parallel cylinders indicated generally at 10a and 10b are. preferably fonned of standard steel tubing. Medially of their ends the inner sides of the tubes are cut out to form interfacing openings having curved side edges 11a and 11b extending transversely of the cylinders, preferably to the longitudinal center lines of the respective tubes; in other words, halfway through the tubes.

- The longitudinal extent of the openings is such as to allow 90 rotation of the dual crank or balanced torque arm 12 which-is keyed at 13 on the valve stem or shaft 14 extending between the cylinders 10a and 10b and transversely to the openings on an axis midway between the openingsThe rotation of the torque arm is from the full line position in FIG. 1 at 45 to the longitudinal axes of the cylinders to an opposite 45 position.

A housing forming a sealed chamber around and between the two interfacing openings completely en'- closes the torque arm 12. The housing is formed by four rectangularly arranged plates welded to the cylinders around the edges of the cut outopenings therein.

The arrangement of the four plates is best shown in FIG. 6 and comprises two parallel spaced-apart rectangular plates 16 extending longitudinally of the cylinders, and two laterally extending parallel spaced-apart concavo-concave plates 17 having linear edges at their upper and lower ends and oppositely curved side edges.

The plates 16 are in planes perpendicular to the axis of the valve stem 14 and are welded along their laterally'outer edges 18 to the longitudinal edges 11a and 11b of the openings 11a and 11b along the tops and bottoms of the cylinders 10a and 10b. The plates 17 extend perpendicular to the plates 16 and their upper and lower linear edges are continuously welded to the longitudinally outer edges 19 of plates 16. The curved side edges 20 of the plates 17 conform and are continuously welded to the longitudinally spaced curved side edges 11a and 11b of the openings, which are in planes perpendicular to said upper and lower linear edges.

As indicated in the drawings, the upper and lower edges of the plates 17 may terminate somewhat short of the longitudinal edges 11a and 11b, the intervening spaces being filled with weld metal, as indicated at 21 in FIG. 3. I

The valve stem 14 is journaled in bearing sleeves 22 extending through the respective rectangular plates 16 Preferably, a mounting ring 27 for supporting the dual cylinder operator on a valve or bracket is welded to the plate 18 surrounding the intermediate portion of the valve stem 14. The ring 27 may have a circular series of bolt holes 28 therein for mounting purposes.

Within each cylinder a and 10b are two pistons 30 and 31 connected in spaced relation by a connector bar 32 and slidably mounted in the cylinder on opposite sides of the openings formed by the cut out edges 11a and 11a and 11b and 11b, respectively. The pistons are of identical construction and only one piston 30 will be described in detail.

The outer periphery of each piston has two bearing bands 34 therein which may be of Teflon and an O-ring seal 35 between the bands. The Teflon bands act as thrust bearings opposing the angular thrust imparted to the bars 32 by the torque of the crank arm 12, and at the same time act as wiper rings to prevent any foreign material from entering between the pistons and their cylinders. The Teflon bands are self-lubricating and 1 hence no lubricating oil need be injected into the cylinders to enhance the gliding movement of the pistons therein.

The connecting bars 32 have cylindrical necks 36 at each end on which the pistons are mounted. The necks extend through the pistons with a positive clearance of about one thirty-second inch all around the bores in the pistons. At the outer face of the hub of each piston, a stud 37 screwed into the neck 36 clamps against a washer 38 to draw the shoulder of the bar against the inner face of the piston hub, with an O-ring seal 39 in the hub face surrounding the neck 36- of the bar. This the positive clearance between the necks 36 of the connecting bars 32 and the pistons 30 and 31 compensates for any slight misalignment of the inner surfaces of the cylinders 10a and 105 due to honing the cylinders from opposite ends, and prevents misalignment and binding of the pistons themselves.

The pistons 30 and 31 alternately abut against the head 42 and 43 of the respective cylinders at the ends of the stroke of the crank arm 12 and adjusting studs 44 are preferably provided in the heads to vary the stroke. The studs preferably have caps 45 which embody sealing O-rings 46 and 47 around the studs and .between the caps and the piston heads.

The heads 42 and 43 have peripheral flanges 48 extending radially outward of the ends of the cylinders, and these flanges are secured by bolts 49 to back up spacer rings 50 welded to the outer ends of the cylinders. The tangential abutment between the spacer rings 50 and head flanges 48 spaces the ends of the cylinders apart the same distance as the width of the narrow medial portions 17 of the plates 17. As shown in FIG. 2, laterally extending weld metal 51 is filled in between the head flanges 48 of the cylinders 10a and 10b to secure them together. The heads 42 and 43 have ports 52 therein for conducting pressure fluid to and from the ends of the cylinders to reciprocate the pistons therein.

The connecting bars 32 have central slots 53 therein formed by side portions 54 which straddle the ends of the crank arm 12, and at the medial portions of the slots roller sleeves 55, preferably of Teflon, having hardened steel outer bushings 56 are journaled on pins 57 extending transversely of the slots and secured at their outer ends in the side portions 54. The ends of the arm 12 have open slots 58 therein extending longitudinally of the bar, and the slots rollablyreceive the bushings 56, providing Scotch yoke connections for transmitting the reciprocating movement of the bars to rotate the bar 12 through approximately In the full line position of the crank arm shown in FIG. 1, the right piston 31 of cylinder 10a is in abutment with head 43 and the left piston of cylinder 10b is in abutment with head 42, the rollers 56 are at the outer ends of slots 58, and the valve stem may be in valve open or valve closed position. If pressure is-introduced through port 52 at the right end of cylinder 10a and through port 52 at the left end of cylinder 10!), the rollers 56 at opposite ends of the arm 12 will rotate the arm counterclockwise through about 90 until the left piston in cylinder 10a abuts head 42, during which stroke the port 52 in said head is open to exhaust. At the same time, the right piston in cylinder 10b abuts the head 43 therein at the end of the stroke. On the return stroke, flow of pressure fluid is reversed to return the pistons and arm 12 to the full line positions of FIG. 1.

Due to the position of the rollers 56 at the outer ends of the slots 58 at the start of the stroke in either direction, the lever arms rotating the valve stem are longest at the start of the stroke when the required torque is greatest. Thus, for example, if the valve element is under high pressure, requiring a high starting torque for opening the valve, the location and arrangement of the rollers and the dual crank or torque arm 12 produces the greatest torque at the start of the opening movement. Moreover, the dual arm with rollers applying equal force to both ends applies a balanced torque to the valve stem.

The four plates 16 and 17 welded to the cylinders around the edges of the interfacing openings therein form a sealed chamber between the cylinders and between the pistons in which the torque arm 12 operates, and provides space for storing an excess supply of pressure fluid. This excess supply may be tapped when needed through a cylinder wall or a fitting in one of the plates.

One way of utilizing the excess stored pressure fluid within the sealed chamber is shown and described in my copending application Ser. No. 072,018, of which this application is a continuation-in-part.

The improved dual cylinder operator utilizes two parallel cylinders and provides a simple and efficient central housing formed of four rectangularly arranged plates and communicating therewith, the housing enclosing a double crank or torque arm for transmitting balanced torque to a valve stem or shaft extending transversely between the cylinders.

I claim:

1. A dual cylinder operator for a rotary element comprising two parallel side-by-side cylinders each being of uniform diameter and having interfacing openings therein intermediate their ends, a pair of axially spaced pistons in each cylinder, a bar connecting each pair of pistons, a rotary shaft extending transversely between operatively connecting said torque arm to said connector bars, and a housing forming a chamber between the cylinders enclosing said torque arm and communicating with said cylinders, said housing being formed of two pairs of parallel spaced-apart plates, the plates of one pair being perpendicular to the plates of the other pair and welded thereto, and the four plates being welded to the cylinders around said interfacing openings therein.

2. A dual cylinder operator as in claim 1, in which the two pairs of plates comprise two axially spaced laterally extending concavo-concave plates and two laterally spaced axially extending rectangular plates welded to the ends of the concave-concave plates.

3. A dual cylinder operator as in claim 2, in which the rotary shaft is journaled in said one pair of rectangular plates.

4. A dual cylinder operator as in claim 2, in which bearing sleeves having flanges bolted to the exteriors of said one pair of rectangular plates extend through said plates and temiinate on opposite sides of said torque arm, said rotary shaft being journaled in said sleeves.

5. A dual cylinder operator as in claim 1, in which the interfacing openings extend substantially halfway through the parallel cylinders.

6. A dual cylinder operator as in claim 1, in which the interfacing openings have outer linear edges parallel with the cylinder axes and said linear edges are connected by curved edges in planes perpendicular to said linear edges.

7. A dual cylinder operator as in claim 6, in which the interfacing openings extend substantially halfway through the parallel cylinders.

8. A dual cylinder operator as in claim 6, in which the housing is formed by one pair of axially spaced laterally extending concave-concave plates welded to said curved edges and one pair of laterally spaced axially extending rectangular plates welded to said linear edges and to said concave-concave plates. 

1. A dual cylinder operator for a rotary element comprising two parallel side-by-side cylinders each being of uniform diameter and having interfacing openings therein intermediate their ends, a pair of axially spaced pistons in each cylinder, a bar connecting each pair of pistons, a rotary shaft extending transversely between said cylinders, a torque arm on said shaft extending laterally into both cylinders through said openings, means operatively connecting said torque arm to said connector bars, and a housing forming a chamber between the cylinders enclosing said torque arm and communicating with said cylinders, said housing being formed of two pairs of parallel spaced-apart plates, the plates of one pair being perpendicular to the plates of the other pair and welded thereto, and the four plates being welded to the cylinders around said interfacing openings therein.
 2. A dual cylinder operator as in claim 1, in which the two pairs of plates comprise two axially spaced laterally extending concavo-concave plates and two laterally spaced axially extending rectangular plates welded to the ends of the concavo-concave plates.
 3. A dual cylinder operator as in claim 2, in which the rotary shaft is journaled in said one pair of rectangular plates.
 4. A dual cylinder operator as in claim 2, in which bearing sleeves having flanges bolted to the exteriors of said one pair of rectangular plates extend through said plates and terminate on opposite sides of said torque arm, said rotary shaft being journaled in said sleeves.
 5. A dual cylinder operator as in claim 1, in which the interfacing openings extend substantially halfway through the parallel cylinders.
 6. A dual cylinder operator as in claim 1, in which the inteRfacing openings have outer linear edges parallel with the cylinder axes and said linear edges are connected by curved edges in planes perpendicular to said linear edges.
 7. A dual cylinder operator as in claim 6, in which the interfacing openings extend substantially halfway through the parallel cylinders.
 8. A dual cylinder operator as in claim 6, in which the housing is formed by one pair of axially spaced laterally extending concavo-concave plates welded to said curved edges and one pair of laterally spaced axially extending rectangular plates welded to said linear edges and to said concavo-concave plates. 